Nowadays an iPhone 12 provides 11 trillion flops, a computing power roughly 900 million times the Apollo 11 guidance computer. Most consumer devices have enough power to boost decentralized applications.

More difficult is the communication across devices because the current Internet infrastructure, with CDN and NAT limitations, supports a client-server paradigm and makes peer-to-peer less reliable and efficient. 

But communication does not need to be decentralized. Decentralized devices, i.e. nodes, can use servers as exchange nodes while computation stays local. Those servers can rely information without the need to understand it.